Metal on My Mind
November 7, 2015 Written by Joe Menth
Talk about living on the edge…
Our attention has been hyper-focused on the edges of big metal prints. The small panels were pressing just fine, but the bigger plates had some issues, until only recently…
We got the capability of dye sublimation printing a few months back, and have been having a blast playing with all of the myriad possibilities provided by such amazing technology.
Well, amazing physics, really.
I wrote up a description of dye sublimation printing, which I can paraphrase here:
Subliming is a physics term. Basically means something goes from a solid state of matter to a gas without going through the liquid stage.
Sublimation is a made up term. Made up by people in the printing industry to riff off of subliming. It means the same thing, but is specifically talking about ink.
So dye sublimation is when there’s ink printed on a special kind of paper, and it’s sandwiched into a heat press at around 400º for a specific amount of time, and the ink sublimes from the paper directly into the specialized coating (usually polyester) on whatever surface one is trying to get the image onto. It can be a metal plate (coated with polyester) or an MDF “wood” panel (also coated with polyester), or a coaster (also…well, you get the idea), or polyester fabric – like a t-shirt.
The crazy thing is what happens on the molecular level: the ink has dispersed – well, it has sublimed – into a gas, and those ink molecules are now floating around, but have really no where to go because of the intense pressure in the heat press…so they can only go in between the molecules of the polyester coating (or fibers in apparel)…and that polyester coating has “glassified”, meaning the molecules started to move away from each other under the great heat, but not quite enough to turn into a liquid.
Anyway. The dye sublimation process is complete when the ink has gasified and embedded itself into the glassified polyester coated surface, and then it’s all cooled. Then it’s kind of bomb-proof. Well, it’s at least quite durable…because SCIENCE.
Moisture is the devil.
At least in this process.
We’ve been “living on the edge” because the edges of our metal prints were giving us a headache. And it wasn’t just the fumes.
You see, when all these materials are sandwiched into a heat press under high pressure, any moisture that exists in the protective paper, in the printed transfer paper, or even in the polyester coating on the metal plate itself, well – it all has to go somewhere. Via steam. Which pushes everything this way and that trying to desperately get out of the sandwich of materials in the heat press.
So it’s a matter of time. Really. It’s a matter of time, and pressure, and heat, and moisture. If it gets too hot too fast, then the steam pushes out too quickly, and it actually pushes those little ink molecules toward the steam escape path, and at the edges of the metal plates, that means the ink gets pushed around and doesn’t alway create a perfectly inked edge.
We struggled with this a bit. We tried different pressure (not enough, and not all the ink would even transfer!), and different heat (not enough, same problem! too much, and we got WAY more steam way too fast).
The solution was a number of variables had to be adjusted simultaneously.
Part of that was fitting a piece of special polyester fabric over the top heat platen so the steam could wick out the sides.
Part of it was pre-heating the big metal panels to allow some moisture to disperse before pressing a printed image onto them. It takes a LOT longer, pre-pressing a panel…and then waiting for it to cool completely before being able to make a print.
But the prints, now…are Awesome.
It’s always so nice to solve a problem that has multiple variables. No one variable can fix it all.
The biggest fix? Patience.
And now we’re no longer living on the edge with bad edges.
And just in time for the JVH Digital Festival printing conference and seminars, of which we ended up being a big part. Oh. Also we got to print some of Art Wolfe‘s work. Woohoo!